I do think that your transportation office handled it poorly. They should have told you that they would look into the matter, not that you would get the service. Personally, I do not think that you should get the service, for the reasons that I already stated, but they should not have led you on, either. I think that, when you get your car back, you should simply drive to the bus stop. If any questions you simply tell them that it's too cold for your little one and that since they will not pick your son up from your house that this is your only other option. Park in such a way that you are not blocking traffic and then don't give it another thought.